1. Field of the Invention
The present invention concerns tokens including contactless electronic microchip identification devices, in particular gaming or casino chips.
2. Discussion of Background Information
Gaming chips are generally fabricated from rigid plastic material resistant to scratching to obtain a robust overall structure. Gaming chips feature varied patterns of designs or colors to form a more or less complex decoration and to reduce the risks of counterfeiting and/or fraudulent reproduction. Moreover the use of color codes and colored patterns associated with the value of the chips, especially on the edge of the chips, enables croupiers or other users to identify and/or sort chips quickly, at a glance, even when stacked up.
To combat fraud and to facilitate counting and tracking of chips, especially in a gaming room or a casino, chips have been proposed incorporating inserts including an electronic circuit with memory in which information associated with the chip is stored, for example its identification number or code and/or its face value. Communication between the electronic circuit module integrated into the chip and its external read/write station is usually effected without contact; a contactless electronic microchip identification device is then used including an electronic microchip or circuit associated with an antenna, generally a circular loop antenna, to enable “contactless” communication with the read/write station using the radio-frequency identification technique.
Originally the electronic microchip (or circuit) was simply connected to the antenna by a basic electrical connection, allowing any movement of the chip in space relative to the antenna or vice-versa. This made the electrical connection very fragile. Thus attempts have been made to immobilize the microchip and the antenna in a casing or to embed the microchip and the antenna in a mass of material to preserve the connection between the microchip and the antenna.
U.S. Pat. No. 4,969,549 (Eglise) describes a payment token usable in public telephone installations in which the electronic circuit and its antenna are encapsulated in a plastic material disk of small diameter, from 20 to 30 mm, the token having a conductive axial core passing through its center.
U.S. Pat. No. 5,166,502 (Rendelman) describes a casino chip in which the antenna and the electronic circuit are disposed inside a metal ballast itself placed between two face plates at the center of an injected plastic material ring, the whole being held in place by epoxy resin and by a second injection covering the ring and the periphery of the plates. This chip is of complex structure and costly to manufacture, however. Moreover, it does not offer all the necessary security in that it is possible to access the electronic circuit by merely cutting one face plate without completely destroying the structure of the chip and rendering it unusable.
The applicant has itself proposed a solution described in U.S. Pat. No. 6,021,949, in which the casino chip includes a central disk consisting of a rigid plastic material shell charged with metallic particles and carrying an electronic identification device and an annular ring of plastic material injected around the disk, said plastic material possibly being charged with mineral particles. In a first variant, the one-piece shell is injected around a protective casing into which the electronic device has previously been integrated. In a second variant the shell is obtained by placing and fastening together the electronic identification device, a cover and a hollow injected plastic material disk. Although giving good results, this technique of manufacturing chips with electronic identification has limitations, especially in terms of the total thickness of a casino chip. Using this technique, it is difficult to reduce the thickness below 3.3 mm (for a diameter that is generally from 39 to 50 mm) and even virtually impossible to achieve the standard chip thickness, which is of the order of 3 mm.
The applicant's U.S. Pat. Nos. 5,895,321 and 6,264,109 disclose chips in the form of disks the body whereof consists of two injected plastic material half-disks with axial projections, defining at the center of the chip a housing for the electronic identifier, the two half-disks being fastened together by the edgewise injection of a plastic material seal.
The electronic identifier of this kind of chip is provided in particular by an electronic circuit connected to an antenna, the circuit and the antenna being attached to a flexible film to protect the electrical connections between the circuit and the antenna.
This kind of electronic identifier is still fragile, however, because of the flexibility of the film carrying the various electronic components. Also, these electronic identifiers were subsequently replaced by rigid plates featuring an electronic microchip connected to an antenna attached to the plate, preferably by printed circuit manufacturing methods, the plate being made from epoxy resin.
The applicant's international application WO 2007/06893 describes a chip having this kind of rigid plate enclosed in a chip body obtained by at least one injection of material around said plate.
Although the chip described in the above application can be made at relatively low cost, it is somewhat fragile, especially where the plate and the core of the chip are fastened together by the first injection of plastic material around the plate.